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MOTIFE Blog

KSeF in practice:
Key information and answers to the most frequently asked questions

By  MOTIFE Insights, 2 March 2026

Changes in the invoicing area are not only a technical matter, but also an organizational and process-related one. The overview below will help you organize the key information and prepare your company for the mandatory KSeF.

Fundamentals and deadlines

What is KSeF?

KSeF (National e-Invoicing System) is a nationwide IT platform used for:

  • issuing structured invoices (in .xml format),
  • receiving invoices,
  • storing invoices within the system.

An invoice becomes an official document once it receives an identification number assigned by KSeF.

When does KSeF become mandatory?

The obligation to issue invoices via KSeF will be introduced in stages:

  • From February 1, 2026 – for the largest entities (sales above PLN 200 million in 2024)
  • From April 1, 2026 – for most taxpayers (sales up to PLN 200 million in 2024)
  • From January 1, 2027 – for the smallest entities (monthly sales up to PLN 10,000)

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Important
‍The obligation to receive invoices via KSeF applies to all businesses already from February 1, 2026, even if they are not yet required to issue invoices through the system.

Do all invoices need to go through KSeF?

Most do — but not all.

Mandatory in KSeF (from 2026):

  • B2B invoices (between businesses)
  • B2G invoices (business to public authority)

Excluded from the system:

  • B2C invoices (consumer sales)
  • Tickets functioning as invoices (rail, public transport, toll roads)
  • OSS and IOSS procedure invoices
  • VAT RR invoices – under specific conditions
  • Receipts with NIP up to PLN 450 – until December 31, 2026
  • Invoices issued from fiscal printers – until December 31, 2026

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Invoice issuing modes under KSeF

KSeF allows several issuing modes, depending on technical circumstances and system availability.

Online mode (default)
This is the standard and recommended mode.

  • The invoice must be sent to KSeF on the same day — either immediately upon issuance or by the end of that day.
  • The visualization includes one QR code.

‍

Offline24 mode
Used in case of minor technical issues on the taxpayer’s side (e.g., no internet connection).

  • The invoice must be sent to KSeF no later than the next business day.
  • The visualization includes two QR codes.

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Offline – KSeF unavailability
Applies during officially announced system maintenance.

  • The invoice must be submitted to KSeF no later than the first business day after the unavailability period ends.
  • The visualization includes two QR codes.

‍

Emergency mode
Used in case of officially announced KSeF system failure (published in BIP and interface software).

  • The invoice must be submitted to KSeF within 7 business days after the failure ends.
  • The visualization includes two QR codes.

What does this mean for your organization?

KSeF impacts more than just invoice format. It affects:

  • accounting workflows,
  • ERP integrations,
  • document circulation processes,
  • operational risk management.

‍

Companies should proactively:

  • assess IT system readiness,
  • review internal procedures,
  • train accounting and operational teams,
  • prepare fallback procedures for system downtime scenarios.

‍

Early preparation significantly reduces operational risk when the mandatory deadlines arrive in 2026.

System operation and integration with KSeF

Beyond the legal obligation itself, successful implementation depends on access management, system integration, and proper authorization structure. Below is a structured overview to support a smooth transition.

How to log in to KSeF (Taxpayer Application)?

Access is free of charge. You can log in using:

  • Trusted Profile (Profil Zaufany),
  • Qualified electronic signature,
  • Electronic seal (for companies).

The appropriate method depends on your legal structure and internal processes.

How can invoices be issued in KSeF?

You have two main options:

Free tools provided by the Ministry of Finance

  • KSeF Taxpayer Application (browser-based)
  • Mobile application

Suitable for smaller volumes or simpler workflows.

Your accounting software
After integration, invoices issued in your system are automatically sent to KSeF.

Most commercial software providers already offer built-in integration, which requires proper configuration.

What does software integration with KSeF mean?

Integration connects your invoicing software directly to the Ministry of Finance servers.

In practice:

  • You issue the invoice in your system,
  • Click “Issue and send to KSeF,”
  • The system automatically transfers the file,
  • KSeF assigns an identification number.

No manual login to the government platform is required.

Available integration methods

To avoid manually re-entering invoices into the government application, your system must be authenticated.

Two methods are available:

  • Token-based integration – available only until the end of 2026
  • Certificate-based integration – target long-term solution

How do tokens and certificates work?

Both are generated in the KSeF Taxpayer Application and then added to your commercial software. After configuration, your system communicates with KSeF automatically.

Token

  • A unique string generated in KSeF (similar to a permanent password).
  • Contains embedded permissions for a specific entity.
  • Anyone using the token operates within the assigned permissions.

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Certificate

  • Also generated in KSeF.
  • Assigned to a specific person or entity.
  • Requires prior authorization in the system.

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For sole traders
The owner already has full rights and may directly generate certificates and integrate them into the software.

For accounting offices
You must grant permissions in KSeF to the specific accountant or firm, who will then integrate the system using their own certificates.

Types of KSeF certificates

There are two certificate types:

Type 1 certificate
Used for everyday authentication and standard system operations.

Type 2 certificate
Required when issuing invoices in special offline modes.

It enables attaching two QR codes that verify the issuer’s identity. Even if token integration is used in 2026, offline modes require a Type 2 certificate.

Technical and tax-related questions

Does a KSeF invoice require a QR code?

A QR code is required when:

  • generating a PDF visualization,
  • sending the invoice outside KSeF (e.g., emergency mode).

Can invoices be issued with a backdated issue date?

No. The relevant date is when the file is accepted by KSeF. Timely issuance — especially at month-end — is therefore critical.

How are errors corrected in KSeF?

Correction notes are no longer applicable.

Any error — including minor spelling mistakes — requires issuing a structured correction invoice in KSeF.

The most reliable source is: podatki.gov.pl/ksef/

Where can official instructions be found?

It provides official guidelines, webinars, and step-by-step materials.

Cooperation with MOTIFE

To ensure operational consistency and timely settlements, please follow the guidelines below.

When is the latest invoice deadline for MOTIFE?

Invoices should be issued no later than the last day of the settlement month.

Should invoices still be sent by email after April 1, 2026?

Yes. Although the invoice is technically considered delivered once it receives a KSeF number, for operational efficiency we kindly request:

  • sending the invoice via KSeF, and
  • simultaneously sending its PDF visualization to the existing email address.

We will communicate separately if email delivery is discontinued.

What happens if I issue an invoice in my software but send it to KSeF a few days later?

The invoice issue date equals the date of submission to KSeF.

Late submissions are considered outside the standard mode and may affect:

  • payment terms,
  • tax settlements.

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What if I experience problems sending the invoice to KSeF?

Offline modes apply in case of technical failure.

In practice:

  • issue the invoice in your system with two QR codes,
  • deliver it to us,
  • submit it to KSeF within the legally defined timeframe for the specific type of failure.

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